•Sections 1 & 2
Section 13-1
Section 13.1 The Gas Laws
•State the relationships among pressure, temperature,and volume of a constant amount of gas.
scientific law: describes a relationship in nature thatis supported by many experiments
•Apply the gas laws to problems involving thepressure, temperature, and volume of a constantamount of gas.
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Section 13-1
Section 13.1 The Gas Laws (cont.)
For a fixed amount of gas, a change inone variable—pressure, temperature,or volume—affects the other two.
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Section 13-1
Boyle's Law
•Boyle’s law states that the volume of a fixedamount of gas held at a constant temperaturevaries inversely with the pressure.
P1V1 = P2V2 where P = pressure and V = volume
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Section 13-1
Charles's Law
•As temperature increases, so does thevolume of gas when the amount of gas andpressure do not change.
•Kinetic-molecular theory explains thisproperty.
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Section 13-1
Charles's Law (cont.)
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Section 13-1
Charles's Law (cont.)
•Charles’s law states that the volume of agiven amount of gas is directly proportional toits kelvin temperature at constant pressure.
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Section 13-1
Gay-Lussac's Law
•Gay-Lussac’s law states that the pressureof a fixed amount of gas varies directly withthe kelvin temperature when the volumeremains constant.
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Section 13-1
Gay-Lussac's Law (cont.)
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Section 13-1
•If all three laws (Boyle’s, Charles’, Gay-Lussac’s) are combined then the resultingequation is the:
states the relationship amongpressure, temperature, andvolume of a fixed amount ofgas.
The Combined Gas Law
In the combined gas law formula, draw a circle around Boyles’ Law, Charles’ Law & Gay-Lussac’s Law. Shade in each circle a different color to distinguish the individual laws that makeup the combined law.
When using the combined gas law, crossout any unnecessary variable.
•Ex) A child’s party inflatable has a pressure of15.8 atm at the beginning of the partywhen the temperature is 33oC. Near theend of the party the temperature drops to17oC. What is the new pressure?
1st: Convert Celsius temperatures to Kelvin units.
Solution:
T1 = 33 + 273 = 306 K
T2 = 17 + 273 = 290. K
The Combined Gas Law (cont.)
2nd: Substitute values into equation.
15.8 atm V1
306 K
=
P2 V2
290. K
3rd: Cross out any variables not mentioned at all.
4th: Cross multiply & solve for the unknown.
(15.8atm) (290. K)
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(306 K) P2
306 K
306 K
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The Combined Gas Law (cont.)
Section 13-1
The Combined Gas Law (cont.)
